JP3032757B1 - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

A non-aqueous electrolyte secondary battery having a high discharge voltage, excellent large-current charge / discharge characteristics, and excellent cycle characteristics. SOLUTION: (A) a positive electrode using a specific lithium nickel composite oxide or lithium manganese composite oxide as a positive electrode active material, (B) a negative electrode containing a compound capable of inserting and extracting lithium ions, and (C) a nonaqueous solution A non-aqueous electrolyte secondary battery comprising an electrolytic solution in which an electrolyte is dissolved in a solvent, wherein the positive electrode active material forms secondary particles composed of primary particles, and the average length of the primary particles in the short direction. A non-aqueous electrolyte secondary battery, wherein a ratio D50 / r between the diameter r and the particle diameter D50 at which the volume cumulative frequency of the particle size distribution of the secondary particles reaches 50% is 10 ≦ D50 / r ≦ 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive electrode active material for a non-aqueous electrolyte secondary battery.

[0002]

2. Description of the Related Art In recent years, with the reduction in size and weight of various electronic devices such as VTRs, mobile phones, and mobile computers, the demand for secondary batteries having a high energy density has increased as a power source for these devices. Research on non-aqueous electrolyte secondary batteries has been actively conducted. Already, LiCoO ₂
Lithium ion secondary batteries using as a positive electrode active material have been put to practical use as secondary batteries with high energy density.

[0003] Non-aqueous electrolyte secondary batteries use lithium as a negative electrode,
Using a lithium alloy or a compound that absorbs and releases lithium ions, propylene carbonate (P
C), ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DM
C), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), γ-butyl lactone (γ-B
L), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), and LiClO ₄ in other non-aqueous electrolyte, LiBF _4, LiAsF _6,
It is composed of LiPF ₆ , LiCF ₃ SO ₃ , LiAlCl ₄ and other lithium salts (electrolytes) dissolved therein. As a positive electrode, an active material utilizing intercalation or doping of a layered compound has attracted attention.

As an example utilizing the intercalation of the layered compound, a chalcogenide compound has relatively excellent charge / discharge cycle characteristics. However,
Chalcogenide compounds have a low electromotive force, and the practical discharge voltage is at most about 2 V even when lithium metal is used as the negative electrode, satisfying the high electromotive force characteristic of nonaqueous electrolyte secondary batteries. Was not.

On the other hand, V ₂ O ₅ , V
Metal oxide-based compounds such as ₆ O ₁₃ , LiCoO ₂ , LiNiO _2, or LiMn ₂ O ₄ utilizing the doping phenomenon have attracted attention because of their high electromotive force characteristics. In particular, a battery using a positive electrode made of LiCoO ₂ or LiNiO ₂ has an electromotive force of about 4 V and a theoretical energy density of about 1 kWh / kg per positive electrode active material. Because of these features, it has been put to practical use as a power source for mobile devices such as mobile phones, which are highly required to be reduced in size or weight. In addition, by increasing the size of the non-aqueous electrolyte secondary battery, it is developed as a non-aqueous electrolyte secondary battery for power storage that stores nighttime power and flattens power consumption, and a power source for hybrid electric vehicles or electric vehicles. Is being promoted.

[0006]

However, non-aqueous electrolyte secondary batteries using the above-mentioned metal oxide compounds and compounds that occlude and release lithium ions are characterized by large current charge / discharge characteristics and cycle characteristics. There was still room for improvement.

[0007]

Means for Solving the Problems] SUMMARY OF THE INVENTION <Summary> The nonaqueous electrolyte secondary battery of the present invention, (A) the general formula _{Li x M 1-y A y} F z O 2n-z ( wherein so,
0.9 ≦ x ≦ 1.1, 0 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.2
5, 1 ≦ n ≦ 2, M is at least one or more transition elements selected from Co, Ni, Mn, A is Co, Ni, Mn,
B, at least one element selected from Al) as a positive electrode active material, (B) a negative electrode containing a compound that absorbs and releases lithium ions, and (C) a non- An electrolyte solution in which an electrolyte is dissolved in a water solvent, wherein the positive electrode active material has a crystal structure with C-axis orientation, forms secondary particles composed of primary particles, and The ratio D50 / r of the length r in the short direction of the particles to the average particle diameter D50 of the secondary particles is 10 ≦ D50 / r ≦ 50.

<Effect> According to the present invention, there is provided a non-aqueous electrolyte secondary battery having a high discharge voltage, excellent large-current charge / discharge characteristics, and excellent cycle characteristics.

[Specific Description of the Invention] <Positive Electrode Active Material> The non-aqueous electrolyte secondary battery of the present invention has a general formula Li _x M _1-y A
_y F _z O _2n-z (where 0.9 ≦ x ≦ 1.1, 0 ≦ y ≦
0.5, 0 ≦ z ≦ 0.25, 1 ≦ n ≦ 2, M is Co, N
i, at least one or more transition elements selected from Mn,
A is at least one element selected from the group consisting of Co, Ni, Mn, B, and Al), and is a composite oxide composed of primary particles having a crystal structure having C-axis orientation. A positive electrode active material is used, wherein secondary particles are formed, and the ratio D50 / r between the length r of the primary particles in the short direction and the average particle diameter D50 of the secondary particles is 10 ≦ D50 / r ≦ 50. Things.

In the present invention, by using such a composite oxide as a positive electrode active material, a non-aqueous electrolyte secondary battery having excellent large current charge / discharge characteristics and excellent cycle characteristics can be provided. LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ used for a conventional positive electrode for a non-aqueous electrolyte secondary battery
It is an object of the present invention to solve the dilemma of improving the large current characteristics, which is a problem with the positive electrode active material, such that the cycle characteristics are deteriorated, and the improvement of the cycle characteristics is deteriorated in the discharge capacity and the large current characteristics.

Such a composite oxide can be synthesized mainly by using LiNiO ₂ or LiMn ₂ O ₄ as follows.

In the above-mentioned positive electrode active material, the lithium nickel composite oxide is formed from a lithium compound such as lithium hydroxide (LiOH) or lithium oxide (Li) as a raw material.
₂ O), lithium carbonate (Li ₂ CO ₃ ), lithium nitrate (LiNO ₃ ), lithium fluoride (LiF), and others, and a nickel compound such as nickel hydroxide [N
i (OH) ₂ ], nickel carbonate (NiCO ₃ ), nickel oxide (NiO), nickel nitrate [Ni (NO ₃ ) ₂ ], and others, with a Li / Ni ratio of 1 or more and 1.25 or less. Water solvent, or acidic aqueous solution,
Alternatively, a reaction is performed in which the slurry is mixed in an alkaline aqueous solution or an organic solvent such as methanol, ethanol, or acetone, and the resulting slurry is kept at a temperature of 650 ° C. to 750 ° C. in an oxidizing atmosphere having an oxygen concentration of 18% to 100%. The composite oxide obtained by spraying into the furnace is subjected to 0.1% oxidation in an oxidizing atmosphere having an oxygen concentration of 18% or more and 100% or less.
Pressurizing not less than MPas and not more than 50 MPas, 450 ° C
It is obtained by performing a heat treatment at 900 ° C. or lower for 1 hour or more and then gradually cooling at a cooling rate of 50 ° C. or lower per hour.

[0013] The lithium manganese composite oxide is prepared by mixing the above lithium compound and manganese oxide (M
manganese compounds such as nO ₂ ) / manganese carbonate (MnCO ₃ ) and manganese nitrate [Mn (NO ₃ ) ₂ ]
Except for mixing so that the ratio of Mn is 0.5 or more and 0.51 or less, it can be synthesized in the same manner as the above-mentioned lithium nickel composite oxide.

In the lithium-nickel composite oxide, nickel is partially replaced with Co, Mn, B, F, Al, L
by at least one or more elements selected from i
In the lithium-manganese composite oxide, by replacing a part of manganese with at least one or more elements selected from Co, Ni, B, F, Al, and Li, an excessive crystal structure accompanying a charge / discharge reaction is obtained. By suppressing the change and controlling the crystal growth of the primary particles of the positive electrode active material, the cycle characteristics can be improved. Furthermore, by combining the spray pyrolysis method with the heating method under high oxygen pressure and the slow cooling method, the size of the primary particles, the c-axis orientation of the trigonal system, and the ordering of the layered structure can be increased, so that the charge-discharge reaction This facilitates diffusion of lithium ions. By controlling the crystallinity of the primary particles, the reaction resistance of the active material is reduced, the discharge potential is increased, and the large current characteristics are improved. Further, the cycle characteristics can be improved by controlling the size of the primary particles.

When replacing with these elements, nickel hydroxide [Ni (OH) ₂ ], nickel carbonate (Ni
CO ₃ ), nickel oxide (NiO), nickel nitrate [N
i (NO ₃ ) ₂ ], cobalt hydroxide [Co (OH) ₂ ], cobalt carbonate (CoCO ₃ ), cobalt oxide (CoO, Co ₂ O ₃ ), nickel nitrate [Co
(NO ₃ ) ₂ ], manganese oxide (M
manganese compounds such as nO ₂ ) / manganese carbonate (MnCO ₃ ) and manganese nitrate [Mn (NO ₃ ) ₂ ]; boric acid (H
₃ BO ₃ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), boron oxide (B ₂ O ₃ ), lithium tetrahydride borate (Li
Boron compounds such as BH ₄ ), lithium fluoride (Li
F), aluminum hydroxide [Al (OH) ₃ ], aluminum oxide (Al ₂ O ₃ ), aluminum sulfate [Al
₂ (SO ₄ ) ₃ ] aluminum nitrate [Al (NO ₃ ) ₃ ] and lithium hydroxide (LiO
H), lithium oxide (Li ₂ O), lithium carbonate (Li ₂
Mixing a lithium compound such as CO ₃ ) and lithium nitrate (LiNO ₃ ) in a water solvent, an acidic aqueous solution, or an alkaline aqueous solution, or an organic solvent such as methanol, ethanol, or acetone so as to have a predetermined molar ratio; The obtained slurry has an oxygen concentration of 18% to 100%.
It is manufactured by spraying in a reaction furnace maintained at a temperature of 650 ° C. or more and 750 ° C. or less in the following oxidizing atmosphere.
Further, the obtained composite oxide has an oxygen concentration of 18% or more and 10% or more.
0.1 MPa or more and 50 MPa in an atmosphere of 0% or less
pressure of 450 ° C or lower and 900 ° C or lower
It is obtained by performing slow cooling at a cooling rate of 50 ° C. or less per hour after performing the heat treatment for at least an hour. Elements M other than Ni and Li obtained by the coprecipitation method (M = Co, M
n, Al) and the surface of the hydroxide with an element M other than Ni (M
= Co, Mn, Al), lithium hydroxide (LiOH), lithium oxide (Li)
₂ O), lithium (Li ₂ CO ₃ carbonate), it may perform the heat treatment a mixture of a lithium compound such as lithium nitrate (LiNO _3).

Alternatively, after mixing LiNiO ₂ or LiMnO ₄ synthesized in advance with a metal compound to be used for substitution at a predetermined molar ratio, heat treatment is carried out, and the mixture is added in an atmosphere having an oxygen concentration of 18% or more and 100% or less. 1MPas or more 5
After applying pressure of 0 MPa or less and performing heat treatment at 450 ° C. or more and 900 ° C. or less for 1 hour or more, the cooling rate is 50 ° C./hour.
It is manufactured by performing the following slow cooling.

By spray pyrolyzing the obtained raw material slurry, a uniform composition distribution can be obtained, and a crystal structure having desired primary particle size and c-axis orientation can be obtained by heating under a high oxygen pressure. can get. In addition, 50 ° C per hour
By slow cooling at the following cooling rate, ordering of the layered structure can be enhanced.

When a part of nickel of LiNiO ₂ is substituted by a substitution element M ′ other than Li, the composition formula is LiNi _1-y
Assuming that M ′ _y O ₂ , it is preferable that 0 ≦ y ≦ 0.5. When y exceeds 0.5, nickel ions easily mix into lithium ion sites, and diffusion of lithium ions during charging and discharging is hindered. As a result, the polarization is increased, the discharge potential is reduced, and the large current charge / discharge characteristics are reduced. Therefore, it is preferable that 0 ≦ y ≦ 0.5. Also, L
When the substitution is performed by i, the composition formula is Li _{1 + p} Ni _1-p O ₂
Then, it is preferable that 0 ≦ p ≦ 0.1. When p exceeds 0.1, the crystal structure becomes unstable and the charge / discharge cycle characteristics deteriorate, so that 0 ≦ p ≦ 0.1 is preferable. Further, when the composition formula when Li and F are simultaneously substituted is Li _{1 + p} Ni _1-p O _{2-z Fz} , 0
It is preferable that ≦ z ≦ 0.25. When z exceeds 0.25, diffusion of lithium ions at the time of charge / discharge is hindered, and the charge / discharge capacity is reduced. More preferably, 0 ≦ z ≦
0.1.

The spray pyrolysis treatment is performed at 650 to 750 ° C. in an oxidizing atmosphere in which the oxygen concentration is 18% or more and 100%.
It is preferable that the temperature is maintained at the temperature. The firing may be performed in a mixed gas of a gas other than oxygen (eg, an argon gas or a nitrogen gas) and oxygen. When the oxygen concentration is lower than 18%, unreacted products such as lithium carbonate and nickel oxide remain on the surface of the particles, and inhibit the lithium ion occlusion / release reaction. Also, if these unreacted products remain,
The discharge potential decreases. On the other hand, when the oxygen concentration exceeds 18%, the amount of unreacted products decreases, a crystal structure with less disorder of lithium ions and nickel ions is obtained, and high values are obtained for both discharge capacity and discharge potential. 65
If the temperature is lower than 0 ° C., the reaction becomes insufficient and unreacted products remain, thereby inhibiting the lithium ion occlusion / release reaction. In addition, lithium ions and nickel ions are easily disordered, and a uniform crystal structure cannot be obtained. In a crystal structure with many disorder, the valence of nickel ions is less than 3. Since the function of maintaining the charge in the crystal at neutral occurs, the amount of lithium ions that can be inserted and extracted decreases. As a result, the charge / discharge capacity decreases. On the other hand, 75
When the temperature exceeds 0 ° C., desorption of oxygen occurs due to a decomposition reaction,
Since nickel oxide having extremely high reaction resistance adheres to the particle surface, the occlusion / release reaction of lithium ions is inhibited. Therefore, the charge / discharge capacity is reduced, and the large current charge / discharge characteristics are also reduced. Therefore, it is preferable to maintain the temperature in the range of 650 to 750 ° C.

After the spray pyrolysis treatment is performed at a temperature in the range of 650 to 750 ° C., an oxygen stream is introduced so that the oxygen concentration is 18% to 1%.
0.1 MPa or more and 50 M in an atmosphere of 00% or less
Heating is performed at a pressure of 450 ° C. or more and 900 ° C. or less for 1 hour or more. In a positive electrode active material with a layered structure, the lithium insertion and extraction reactions are performed in the direction perpendicular to the trigonal c-axis, so it is extremely important that the lithium ion and nickel ions have a crystal structure with little disorder. It is.

If the heat treatment is performed at a pressure of 0.1 MPa or less, deoxidation occurs, and nickel oxide and lithium carbonate are likely to remain, thereby inhibiting the lithium ion occlusion / release reaction. Therefore, the charge / discharge capacity is reduced, and the large current charge / discharge characteristics are also reduced. On the other hand, 50MPas
When the heat treatment is performed as described above, distortion occurs in the crystal, and structural deterioration is induced as the charge / discharge cycle progresses. Therefore, by performing the heat treatment at 0.1 MPas or more and 50 MPas or less (oxygen partial pressure 0.018 MPas or more and 50 MPas or less), a high value is obtained for both the discharge capacity and the discharge potential.

In the present invention, the ratio D50 / r between the length r of the primary particles in the short direction and the average particle diameter D50 of the secondary particles is 10 ≦ D50 / r by performing the heating under high oxygen pressure after the spray pyrolysis treatment. Controlling the size of the primary and secondary particles so that ≦ 50,
In addition, the trigonal c-axis orientation of the primary particle crystals is improved, and the ordering of the layered structure proceeds by performing the slow cooling method, thereby facilitating the diffusion of lithium ions accompanying the charge / discharge reaction. . Specifically, when the length of the primary particles in the short direction is less than 0.1 μm, expansion and contraction of the crystal due to the charge / discharge reaction are easily alleviated, and the cycle characteristics are improved. However, when forming the secondary particles, the interface between the primary particles increases, and the reaction resistance increases. As a result, the discharge potential decreases, and the large current characteristics also decrease. On the other hand, if the length of the primary particles in the short direction is 1 μm or more, expansion and contraction of the crystal due to the charge / discharge reaction are difficult to relax, and the cycle characteristics are reduced. However, the reaction resistance is reduced because the interface between the primary particles is reduced when forming the secondary particles. As a result, the discharge potential increases, and the large current characteristics are improved. Therefore, the length r of the primary particles in the short direction is preferably 0.1 μm or more and 1 μm or less.

In the present invention, the average particle diameter D50 of the secondary particles of the composite oxide is 50% by volume cumulative frequency of the particle size distribution.
Mean particle size reaching Particle size distribution D10, D50, D9 of volume accumulation frequency 10, 50, 90% of particle size distribution
0 is preferably 0.3 ≦ (D10 / D50) ≦ 0.8 and 1 ≦ (D90 / D50) ≦ 3. When D10 / D50 is less than 0.3, it indicates that many fine particles are contained. If there are many fine particles, the cycle characteristics may be significantly reduced. When D10 / D50 exceeds 0.8, D90 / D50
When D50 / D50 is less than 1, when D90 / D50 is more than 3, when the electrode is manufactured, the filling amount of the active material is reduced and the discharge capacity of the battery may be reduced. Therefore, it is preferable that D10 / D50 is 0.4 or more and 0.8 or less, and D90 / D50 is 1 or more and 3 or less.

It is preferable that D50 is 0.2 μm or more and 50 μm or less. When D50 is less than 0.2 μm, crystal growth becomes insufficient, and a sufficient discharge capacity may not be obtained. When D50 exceeds 50 μm, it may be difficult to obtain a uniform electrode surface when producing an electrode. Therefore, the average particle size D5
0 is preferably 0.2 μm or more and 50 μm or less.

In the present invention, as a method for satisfying both of the above contradictory characteristics, the ratio D50 / r of the length r of the primary particles of the positive electrode active material in the short direction to the average particle diameter D50 of the secondary particles of the present invention is 10 ≦ D50 / r ≦ 50, the discharge potential is high and excellent in large current characteristics,
In addition, a positive electrode active material having excellent cycle characteristics can be obtained. More preferably, 20 ≦ D50 / r ≦ 40. The length r of the primary particles in the short direction of the positive electrode active material and the average particle diameter D5 of the secondary particles
0 can be easily obtained by SEM observation, wet or dry powder particle size distribution measurement.

Further, Miller index h of powder X-ray diffraction using CuKα ray of the composite oxide which can be used in the present invention.
FWHM (003) and FWHM (1) of the diffraction peaks at the (003) and (104) planes at kl
The relationship of 04) is as follows: 0.7 ≦ FWHM (003) / FWEM (104) ≦
It is preferably 0.9.

FWHM (003) / FWHM (104)
Is less than 0.7, it indicates that crystal growth in the direction perpendicular to the c-axis is inferior to the trigonal c-axis orientation and the ordering of the layered structure. It has been confirmed that the expansion and contraction of the crystal due to the charge / discharge reaction occurs in the c-axis and a-axis directions. In particular, a difference in expansion and contraction occurs in a direction orthogonal to the c-axis, and thus the cycle characteristics may be reduced. is there. Therefore, FWHM (003) / FWHM (104) is equal to 0.
It is preferably 7 or more. On the other hand, FWHM (00
3) When / FWHM (104) exceeds 0.9, it indicates that the c-axis orientation of the trigonal system and the ordering of the layered structure have not progressed. In this case, the diffusion of lithium ions is hindered and the diffusion movement distance is increased, so that the reaction resistance is increased, the discharge potential is reduced, and the large current charge / discharge characteristics may be reduced. Therefore, FWHM (O03) /
FWHM (104) is preferably 0.9 or less.

Further, FWHM (003) and FWHM
(104) preferably satisfies 0.1 ≦ FWHM (003) ≦ 0.16 ゜ 0.13 ゜ ≦ FWHM (104) ≦ 0.2 ゜, respectively, and 0.12 ゜ ≦ FWHM (003). It is more preferable that ≦ 0.15Ｆ0.14 （≦ FWHM (104) ≦ 0.17 ゜. When the FWHM (003) of the composite oxide in the present invention is within this range, high values are obtained for both the discharge capacity and the discharge potential. On the other hand, FWHM
(104) can be controlled within this range by, for example, performing a high oxygen pressure heating method. This indicates that crystal growth in the direction perpendicular to the trigonal c-axis was suppressed.

Further, the diffraction peak intensity I (0
03) and I (104) are in the range of 0.25 ≦ I (10
4) It is preferable that /I(003)≦0.8. I
When (104) / I (003) is less than 0.25, the c-axis orientation of the crystal is remarkably increased, and lithium is easily absorbed and released, but a reaction with the electrolytic solution easily occurs on the surface of the active material particles. . Also, I (104) / I (003)
Exceeds 0.8, it indicates that the ordering of the trigonal c-axis orientation and the layered structure has not progressed. In this case, the diffusion of lithium ions is hindered and the diffusion movement distance increases, so that the reaction resistance increases, the discharge potential decreases, and the large current charge / discharge characteristics decrease. Therefore, I
(003) / I (104) is preferably 0.25 or more and 0.8 or less.

The average valence of nickel in the positive electrode active material is preferably 2.9 or more and 3.1 or less. When the average valence of nickel is less than 2.9, it indicates that a large amount of divalent nickel is contained in the crystal. Divalent nickel is mixed into lithium sites to prevent the diffusion of lithium during charge and discharge, and at the same time, the total amount of chargeable and dischargeable lithium ions decreases, so that a sufficient discharge capacity cannot be obtained. When the average valence of nickel exceeds 3.1, it indicates that lithium is deficient. Also in this case, a sufficient discharge capacity cannot be obtained because the total amount of chargeable and dischargeable lithium ions is reduced. Therefore, it is preferable that the average valence of nickel is 2.9 or more and 3.1 or less.

The non-aqueous electrolyte secondary battery according to the present invention has a general formula Li _x M _{1 -y Ay} B _z O _2n -z (0.9 ≦ x ≦ 1.1, 0 ≦
y ≦ 0.5, 0 ≦ z ≦ 0.25, 1 ≦ n ≦ 2), M is at least one or more transition elements selected from Co, Ni, Mn, and A is Co, Ni, Mn, B, At least one or more elements selected from Al, B has a positive electrode including at least one particle of particles mainly composed of a composite oxide composed of F, and the particles form secondary particles composed of primary particles. And the ratio D50 / r between the length r of the primary particles in the short direction and the average particle diameter D50 of the secondary particles is 10 ≦ D50.
/ R ≦ 50. By using a positive electrode containing such particles, expansion and contraction of the crystal due to the charge / discharge reaction are easily alleviated, and the cycle characteristics are improved. Furthermore, the reaction resistance is reduced because the interface between the primary particles is reduced when forming the secondary particles. As a result, a non-aqueous electrolyte secondary battery having an increased discharge potential and improved large current characteristics can be provided.

Further, nickel, nickel, cobalt, Mn, B, Al,
By using at least one element selected from the group consisting of F and Li, it is possible to prevent the crystal from being distorted due to the insertion and extraction of lithium ions, so that the charge / discharge cycle characteristics are dramatically improved. An electrolyte secondary battery can be provided. Further, Co, Ni, B, Al, F are substituted elements for manganese contained in the lithium manganese composite oxide.
And at least one element selected from Li, it is possible to suppress the distortion of the crystal due to the insertion and extraction of lithium ions, so that the non-aqueous electrolysis with significantly improved charge / discharge cycle characteristics. A liquid secondary battery can be provided.

<Structure of Battery> A non-aqueous electrolyte secondary battery (for example, a cylindrical non-aqueous electrolyte secondary battery) according to the present invention will be described in detail with reference to FIG.

For example, a cylindrical container 1 having a bottom made of stainless steel has an insulator 2 disposed at the bottom. Electrode group 3
Are stored in the container 1. The electrode group 3 includes:
It has a structure in which a belt-like material in which the positive electrode 4, the separator 5, and the negative electrode 6 are laminated in this order is spirally wound so that the negative electrode 6 is located outside. The separator 5 is formed of, for example, a nonwoven fabric, a polypropylene microporous film, a polyethylene microporous film, or a polyethylene-polypropylene microporous laminated film.

The container 1 contains an electrolytic solution. The insulating paper 7 having a central portion opened is placed above the electrode group 3 in the container 1. The insulating sealing plate 8
The sealing plate 8 is disposed at the upper opening of the container 1 and caulked in the vicinity of the upper opening inward.
Is fixed to the container 1 in a liquid-tight manner. The positive terminal 9 is
It is fitted to the center of the insulating sealing plate 8. One end of the positive electrode lead 10 is connected to the positive electrode 4, and the other end is connected to the positive electrode terminal 9. The negative electrode 6 is connected to the container 1 as a negative electrode terminal via a negative electrode lead (not shown).

Next, the positive electrode 4, the negative electrode 6, and the electrolyte will be specifically described. a) Positive Electrode 4 The positive electrode 4 is obtained by suspending a conductive agent and a binder in the above-described positive electrode active material in an appropriate solvent, and applying the mixture slurry to a substrate serving as a current collector on one side or both sides in a desired size. It is produced by applying a continuous or desired length and an uncoated portion alternately to an area larger than that, drying and thinning the sheet into a desired size. The positive electrode is prepared by kneading the positive electrode active material together with a conductive agent and a binder, or kneading the positive electrode active material together with a conductive material and a binder, and adhering a sheet to the current collector. 4 is produced.

Examples of the conductive agent include acetylene black, carbon black, graphite, and others.

Examples of the binder include polyvinylidene fluoride (PVdF), a vinylidene fluoride-6-propylene propylene copolymer, a vinylidene fluoride-tetrafluoroethylene-6-propylene propylene terpolymer, and a fluorine-containing copolymer. Vinylidene fluoride-pentafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer,
Tetrafluoroethylene-vinylidene fluoride copolymer,
Tetrafluoroethylene-perfluoroalkylvinyl ether (PFA) -vinylidene fluoride terpolymer,
Tetrafluoroethylene-bexafluoropropylene (FEP) -vinylidene fluoride terpolymer, tetrafluoroethylene-ethylene-vinylidene fluoride terpolymer, chlorotrifluoroethylene-vinylidene fluoride copolymer, chlorotriene Fluoroethylene-ethylene-vinylidene fluoride terpolymer, vinyl fluoride-vinylidene fluoride copolymer, ethylene-propylene copolymer (EPDM), styrene butadiene rubber (SB
R), and others.

The positive electrode active material in the mixture slurry,
The mixing ratio of the conductive agent and the binder is 80 to 95% by weight of the positive electrode active material, 3 to 20% by weight of the conductive agent, and 2 to 2% by weight of the binder.
Preferably it is in the range of 10% by weight. In particular, it is preferable that the amount of the positive electrode active material is in the range of 100 to 400 g / m ² as a coating amount on only one side in a state where the positive electrode 4 is manufactured.

As the current collector, for example, aluminum foil, stainless steel foil, titanium foil, and others can be used. Is most preferred. At this time, the thickness of the foil is 10 μm.
It is preferably at least 30 μm.

The positive electrode active material preferably has an average diameter D50 in the range of 0.2 to 50 μm in consideration of adhesion to the substrate and electrochemical characteristics at the time of manufacturing the electrode.
More preferably, it is 0. Further, the specific surface area of the positive electrode active material is preferably 0.2 to ² m ² / g. If the specific surface area is less than 0.2 m ² / g, the packing density of the positive electrode active material may be reduced at the time of producing an electrode, and a sufficient discharge capacity may not be obtained. further,
The charge / discharge efficiency may decrease due to the decrease in the reaction area. On the other hand, when the specific surface area exceeds 2 m ² / g, the decomposition reaction of the electrolyte tends to occur as the reaction area increases, and further, the decomposition reaction of the cathode active material proceeds due to the reaction between the cathode active material and the electrolyte. However, when the battery is abnormal such as overcharging, the battery is likely to generate abnormal heat, burst or fire.

B) Negative Electrode 6 The negative electrode 6 contains a compound that stores and releases lithium ions. Examples of the compound that occludes and releases lithium ions include, for example, lithium ion-doped polyacetal, polyacetylene, polypyrrole, and other conductive polymers, carbon materials made of lithium ion-doped organic sintered bodies, and others. be able to.

The characteristics of the carbon material vary considerably depending on the raw material and the firing method. For example, graphite-based carbon, carbon having a mixture of graphite crystal parts and amorphous parts, and a carbon material having a turbostratic structure having no regularity in the crystal layer stack can be used.

The negative electrode containing the carbon material is specifically manufactured by the following method. A binder is suspended in an appropriate solvent in the carbon material, and the mixture slurry is applied to a current collector on one side,
Or apply to the area larger than the desired size on both sides alternately with continuous or desired length and uncoated part,
The dried and thin plate is cut into a desired size and produced. Further, pellets formed by molding the carbon material with a binder, or kneading the carbon material with a binder,
The sheet is attached to the current collector to produce the negative electrode. Examples of the binder include polyvinylidene fluoride (PVdF), vinylidene fluoride-6-propylene propylene copolymer, vinylidene fluoride-tetrafluoroethylene-6-propylene fluorinated terpolymer, and vinylidene fluoride- Pentafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, tetrafluoroethylene-vinylidene fluoride copolymer, tetrafluoroethylene-perfluoroalkylvinyl ether (PFA) -vinylidene fluoride terpolymer , Tetrafluoroethylene-bexafluoropropylene (FE
P) -vinylidene fluoride terpolymer, tetrafluoroethylene-ethylene-vinylidene fluoride terpolymer,
Chlorotrifluoroethylene-vinylidene fluoride copolymer, chlorotrifluoroethylene-ethylene-vinylidene fluoride terpolymer, vinyl fluoride-vinylidene fluoride copolymer, ethylene-propylene-diene copolymer (EPDM) And styrene-butadiene rubber (SBR).

The mixing ratio of the negative electrode material and the binder is preferably in the range of 80 to 98% by weight of the negative electrode material and 2 to 20% by weight of the binder. In particular, in the state where the negative electrode 6 is manufactured, the carbon material is applied in an amount of 50 to 200 g /
It is preferred to be in the range of m ² . As the current collector, for example, a copper foil, a nickel foil, and others can be used, but a copper foil is most preferable in consideration of electrochemical stability, flexibility at the time of winding, and the like. At this time, the thickness of the foil is preferably 8 μm or more and 20 μm or less.

C) Electrolytic Solution The electrolytic solution has a composition in which an electrolyte is dissolved in a non-aqueous solvent. Examples of the non-aqueous solvent include propylene carbonate (PC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC),
Dimethoxyethane (DME), diethoxyethane (D
EE), γ-butyrolactone (γ-BL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxolan, 1,3-
One or a mixture of two or more selected from dimethoxypropane can be mentioned. Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), and lithium arsenide hexafluoride (LiA
sF ₆ ), lithium hexafluorophosphate (LiPF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ),
One or more lithium salts selected from lithium aluminum tetrachloride (LiAlCl ₄ ) can be given. The amount of the electrolyte dissolved in the non-aqueous solvent is
Preferably it is 0.5 to 1.5 mol / l.

[0047]

EXAMPLE 1 A nickel hydroxide powder having a molar ratio of Li: Ni of 1.02:
1 and a 3 mol / L aqueous solution of lithium hydroxide was added dropwise. After mixing well, the oxygen concentration was 1
Spraying into a reaction furnace maintained at a temperature of 700 ° C. while introducing an oxygen stream so as to be 8% or more and 100% or less,
The obtained product is held so that the oxygen concentration becomes 95% or more, and then 800 while pressing to 1 MPa.
Heat treatment was performed at 5 ° C. for 5 hours. When the obtained product was measured by X-ray diffraction, it was confirmed that LiNiO ₂ was present. After 90% by weight of the LiNiO ₂ powder and 5% by weight of acetylene black were mixed in a ball mill for 1 hour,
Polyvinylidene fluoride was dissolved in N-methylpyrrolidone so as to be 5% by weight, the temperature was 10 ° C, and the humidity was 20%.
A mixture slurry was prepared while maintaining the following conditions. This mixture slurry was applied to an aluminum foil, dried, and roll-pressed to produce a positive electrode.

The mesoface pitch-based carbon fiber was graphitized at 3000 ° C. in an argon gas atmosphere, and heat-treated in a chlorine gas atmosphere at 2400 ° C. to synthesize a graphitized carbon powder. Subsequently, 94% by weight of the graphitized carbon powder and 6% by weight of polyvinylidene fluoride were dissolved in N-methylpyrrolidone to prepare a mixture slurry. This mixture slurry was applied to a copper foil, dried, and roll-pressed to produce a negative electrode.

After laminating the positive electrode, the separator made of a microporous film made of polypropylene, and the negative electrode in this order, a spirally wound electrode group was prepared so that the negative electrode was the outermost periphery. Further, LiPF6 was dissolved at a concentration of 1.0 mol / liter in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (mixing volume ratio of 1: 2) to prepare an electrolytic solution. Each of the electrode groups and the electrolyte was housed in a stainless steel bottomed cylindrical container to assemble the cylindrical nonaqueous electrolyte secondary battery shown in FIG. 1 described above.

Example 2 A cobalt coprecipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ was mixed at a molar ratio of Li: (Ni + Co) of 1.02: 1, and 3 mol / l. After the lithium hydroxide aqueous solution was dropped and thoroughly mixed, the mixture was sprayed into a reaction furnace maintained at a temperature of 700 ° C. while introducing an oxygen stream so that the oxygen concentration became 18% or more and 100% or less. After the obtained product was held so that the oxygen concentration was 95% or more, a heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, LiNi _0.83 Co
It was confirmed that there was _0.17 O ₂ . LiNi _0.83 obtained
The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 described above was assembled in the same manner as in Example 1 except that Co _0.17 O ₂ powder was used as the positive electrode active material.

Example 3 Nickel nitrate powder, cobalt nitrate powder and aluminum nitrate powder were mixed at a molar ratio of Ni: Co: Al of 0.81:
An aqueous solution of 3 mol / l sodium hydroxide was added dropwise to the mixture mixed so as to be 0.17: 0.02, and
The reaction was continuously carried out while maintaining the temperature at 0 to 60 ° C while carrying the frame. To the obtained product, a 3 mol / L aqueous solution of lithium hydroxide was added dropwise so that the molar ratio of Li: (Ni + Co + Al) became 1.02: 1, and after sufficient mixing, the oxygen concentration was 18% or more. While introducing an oxygen gas stream so as to be 100% or less, it is sprayed into a reaction furnace maintained at a temperature of 700 ° C., and the obtained product is maintained so that the oxygen concentration becomes 95% or more. Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa.

When the obtained product was measured by X-ray diffraction, it was confirmed to be LiNi _0.81 Co _0.17 Al _0.02 O ₂ .

The obtained LiNi _0.81 Co _0.17 Al _0.02 O
A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the _two powders were used as the positive electrode active material.

Example 4 Co-precipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ and aluminum hydroxide were mixed with Al: (N
i + Co) in a molar ratio of 0.01: 1 and dispersed in a 1 mol / l aluminum nitrate aqueous solution, 1 liter / l sodium hydroxide aqueous solution was added dropwise to the mixture at a temperature of 40-60. The reaction was continuously carried out while maintaining the temperature at 0 ° C while stirring, and the surface was coated with aluminum hydroxide. The obtained product was added to Li: (Ni + Co + A
3 mol / L lithium hydroxide aqueous solution was added dropwise so that the molar ratio of 1) became 1.02: 1, and after sufficient mixing, an oxygen stream was supplied so that the oxygen concentration became 18% or more and 100% or less. While introducing the mixture, it was sprayed into a reaction furnace maintained at a temperature of 700 ° C., and the obtained product was maintained at an oxygen concentration of 95% or more. Heat treatment was performed. When the obtained product was measured by X-ray diffraction, LiNi _0.82
It was confirmed to be Co _0.17 Al _0.01 O ₂ . A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained LiNi _0.82 Co _0.17 Al _0.01 O ₂ powder was used as a positive electrode active material.

Example 5 A 3 mol / L aqueous solution of manganese nitrate was prepared by dispersing nickel hydroxide powder so that the molar ratio of Mn: Ni was 1: 4. Was added dropwise, and the mixture was continuously reacted while maintaining the temperature at 40 to 60 ° C. while stirring. In the obtained product, Li:
3 so that the molar ratio of (Ni + Mn) becomes 1.02: 1.
A mole / liter aqueous solution of lithium hydroxide was dropped and mixed well. Then, while introducing an oxygen gas stream so that the oxygen concentration became 18% or more and 100% or less, the reactor was kept at 700 ° C. in a reaction furnace. After spraying and maintaining the oxygen concentration to be 95% or more, a heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, LiNi _0.8 Mn
It was confirmed to be _0.2 O ₂ . LiNi obtained
Except that _0.8 Mn _0.2 O ₂ powder was used as the positive electrode active material,
The cylindrical nonaqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1.

Example 6 The molar ratio of Li: Ni: F was 1.05: 0.95: 0.0.
After sufficiently mixing a dispersion of nickel hydroxide powder and lithium fluoride in a 3 mol / l aqueous solution of lithium hydroxide so as to obtain an oxygen concentration of 18% to 10%.
While introducing an oxygen stream so as to be 0% or less, 700
Sprayed into a reactor maintained at a temperature of
After maintaining the pressure at 5% or more, a heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, Li
_1.05 Ni _0.95 O _1.95 F _0.05 was confirmed. A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained Li _1.05 Ni _0.95 O _1.95 F _0.05 powder was used as a positive electrode active material.

[0057] Example 7 Ni _0.83 Co _0.17 (OH) cobalt Co submerged nickel oxide powder represented by ₂ and lithium tetraborate (Li ₂ B ₄ 0 ₇₎
Are mixed so that the molar ratio of B: (Ni + Co) becomes 1.02: 1, and then 3 mol / liter of lithium hydroxide such that the molar ratio of Li: (Ni + Co + B) becomes 1.02: 1. After the aqueous solution was dropped and thoroughly mixed, the mixture was sprayed into a reaction furnace maintained at a temperature of 700 ° C. while introducing an oxygen stream so that the oxygen concentration became 18% or more and 100% or less. %, And then heat-treated at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiNi _0.81 Co _0.17 B _0.02 O ₂ . The obtained LiNi _0.81 Co _0.17 B _0.02 O ₂
The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the powder was used as the positive electrode active material.

Example 8 Co-precipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ and lithium fluoride were mixed with Li: Ni: C
When the molar ratio of o: F is 1.05: 0.81: 0.17: 0.
After thoroughly mixing the solution dispersed in a 3 mol / L aqueous solution of lithium hydroxide so as to obtain an oxygen concentration of 1
Spraying into a reaction furnace maintained at a temperature of 700 ° C. while introducing an oxygen stream so as to be 8% or more and 100% or less,
After maintaining the oxygen concentration to be 95% or more,
Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was confirmed to be Li _1.05 Ni _0.81 Co _0.17 O _1.95 F _0.05 . The obtained Li _1.05 Ni _0.81 Co _0.17 O
_The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that _1.95 F _0.05 powder was used as the positive electrode active material.

Example 9 A cobalt coprecipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ was mixed with 3 mol / liter of nitric acid so that the molar ratio of Mn: (Ni + Co) became 0.02: 1. A 3 mol / l aqueous solution of sodium hydroxide was added dropwise to the dispersion in the manganese aqueous solution, and the mixture was continuously reacted while maintaining the temperature at 40 to 60 ° C while stirring. The obtained product has a molar ratio of Li: (Ni + Co + Mn) of 1.0.
A 3 mol / L aqueous solution of lithium hydroxide was added dropwise so as to have a ratio of 2: 1. After thoroughly mixing, the oxygen concentration was reduced to 18%.
While introducing an oxygen stream so that the oxygen concentration becomes not less than 100%, it is sprayed into a reaction furnace maintained at a temperature of 700 ° C., and the oxygen concentration is maintained so that the oxygen concentration becomes 95% or more.
Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to MPas. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiNi _0.81 Co _0.17 Mn _0.02 O ₂ . The obtained LiNi _0.81 Co _0.17 Mn _0.02 O ₂
The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the powder was used as the positive electrode active material.

Example 10 A cobalt coprecipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ , aluminum hydroxide and lithium tetraborate were mixed at a molar ratio of B: Al: Mn: (Ni + Co) of 0.1. 02: 0.02: 0.03: 1 in a 3 mol / L manganese nitrate aqueous solution,
A 3 mol / L aqueous solution of sodium hydroxide was added dropwise, and the reaction was continuously carried out with stirring at a temperature of 40 to 60 ° C. Li: (Ni + Co + Mn) was added to the obtained product.
+ Al + B) was added dropwise to a 3 mol / liter aqueous lithium hydroxide solution such that the molar ratio of the mixture became 1.02: 1, and after sufficient mixing, an oxygen stream was supplied so that the oxygen concentration became 18% or more and 100% or less. While introducing, it is sprayed into a reaction furnace maintained at a temperature of 700 ° C., and maintained so that the oxygen concentration becomes 95% or more.
Heat treatment was performed at 00 ° C. for 5 hours. The resulting product is X
As measured by X-ray diffraction, LiNi _0.77 Co _0.16 M
It was confirmed that n _0.03 Al _0.02 B _0.02 O ₂ . The obtained LiNi _0.77 Co _0.16 Mn _0.03 Al _0.02 B _0.02 O
_The cylindrical nonaqueous electrolyte secondary battery shown in FIG. 1 described above was assembled in the same manner as in Example 1 except that the _two powders were used as the positive electrode active material.

Example 11 Co-precipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ , aluminum hydroxide, lithium tetraborate and lithium fluoride were mixed with Li: B: Al: F: Mn:
The molar ratio of (Ni + Co) is 1.05: 0.02: 0.0.
2: 0.05: 0.03: 0.95 dispersed in a 3 mol / L manganese nitrate aqueous solution so as to be:
A 3 mol / L aqueous solution of sodium hydroxide was added dropwise, and the reaction was continuously carried out with stirring at a temperature of 40 to 60 ° C. Li: (Ni + Co + Mn) was added to the obtained product.
+ Al + B + F), a 3 mol / L aqueous solution of lithium hydroxide was added dropwise so that the molar ratio was 1.05: 0.95, and after sufficient mixing, the oxygen concentration was from 18% to 100%.
While introducing an oxygen stream so as to be as follows, it was sprayed into a reaction furnace maintained at a temperature of 700 ° C., and the oxygen concentration was 95%
After holding as described above, a heat treatment was performed at 800 ° C. for 5 hours while pressing to 1 MPa. When the obtained product was measured by X-ray diffraction, Li _1.05 Ni
It was confirmed that the _ratio was _0.75 Co _0.15 Mn _0.03 Al _0.02 B _0.02 F _0.05 0 _1.95 . The obtained Li _1.05 Ni _0.75 Co
FIG. 1 described above in the same manner as in Example 1 except that _0.15 Mn _0.03 Al _0.02 B _0.02 F _0.05 O _1.95 powder was used as the positive electrode active material.
Was assembled.

Comparative Example 1 A positive electrode active material having a D50 / r of 100 or more (r: 0.1, D50: 10.0) Co-precipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ and hydroxide Aluminum and Al: (N
A 3 mol / l sodium hydroxide aqueous solution was added dropwise to a dispersion of 1 mol / l aluminum nitrate aqueous solution such that the molar ratio of (i + Co) became 0.01: 1, and the temperature was maintained at 40 to 60 ° C. The reaction was continued while stirring, and the surface was covered with aluminum hydroxide. The obtained product and lithium hydroxide are mixed with Li: (Ni + Co +
Al) is sufficiently mixed by a ball mill so as to have a molar ratio of 1.02: 1. Then, a mixed gas stream of argon and oxygen is supplied at an hourly rate so that the oxygen concentration becomes 10% or more and 15% or less.
While introducing 0 liter, heat treatment was performed at a temperature of 800 ° C. for 5 hours. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiNi _0.82 Co _0.17 Al _0.01 O ₂ . The obtained iNi _0.82 Co _0.17 Al _0.01
The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the O ₂ powder was used as the positive electrode active material.

Comparative Example 2 A positive electrode active material having a D50 / r of less than 10 (r: 1.0, D50: 8.0) Co-precipitated nickel hydroxide powder represented by Ni _0.83 Co _0.17 (OH) ₂ and hydroxide Aluminum and Al: (N
A 3 mol / l sodium hydroxide aqueous solution was added dropwise to a dispersion of 1 mol / l aluminum nitrate aqueous solution such that the molar ratio of (i + Co) became 0.01: 1, and the temperature was maintained at 40 to 60 ° C. The reaction was continued while stirring, and the surface was coated with aluminum hydroxide. The obtained product and lithium hydroxide are mixed with Li: (Ni + Co +
A 3 mol / L aqueous solution of lithium hydroxide was added dropwise so that the molar ratio of (Al) was 1.02: 1, and after sufficient mixing, spray drying was performed. The resulting dried product is kept at a temperature of 710 ° C. for 48 hours while introducing an oxygen stream so that the oxygen concentration becomes 18% or more and 100% or less. Was held at 95% or more, and then a heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was found that LiNi _0.82 Co _0.17
It was confirmed to be Al _0.01 O ₂ . LiN obtained
The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that i _0.82 Co _0.17 Al _0.01 O ₂ powder was used as the positive electrode active material.

Example 12 Manganese nitrate powder and lithium nitrate powder were mixed such that the molar ratio of Li: Mn was 1: 1.95, and sufficiently dispersed using ethanol as a solvent. While introducing an oxygen stream so as to be at least 100% or less,
It is sprayed into a reaction furnace maintained at a temperature of 700 ° C., and the obtained product is maintained so that the oxygen concentration becomes 95% or more. Then, a heat treatment is performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. Was. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn ₂ O ₄ . A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained LiMn ₂ O ₄ powder was used as a positive electrode active material.

Example 13 A mixture of manganese nitrate powder, cobalt nitrate powder and lithium nitrate powder having a molar ratio of Li: Mn: Co of 1.02: 1.
8: 0.2 and sufficiently dispersed using ethanol as a solvent, and then the oxygen concentration is 18% or more and 100%.
Spraying into a reactor maintained at a temperature of 700 ° C. while introducing an oxygen gas stream as described below, and maintaining the resulting product so that the oxygen concentration becomes 95% or more,
Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn _1.8 Co _0.2 O ₄ . The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 described above was assembled in the same manner as in Example 1, except that the obtained LiMn _1.8 Co _0.2 O ₄ powder was used as a positive electrode active material.

Example 14 A mixture of manganese nitrate powder, nickel nitrate powder and lithium nitrate powder having a molar ratio of Li: Mn: Ni of 1.02: 1.
8: 0.2 and sufficiently dispersed using ethanol as a solvent, and then the oxygen concentration is 18% or more and 100%.
Spraying into a reactor maintained at a temperature of 700 ° C. while introducing an oxygen gas stream as described below, and maintaining the resulting product so that the oxygen concentration becomes 95% or more,
Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn _1.8 Ni _0.2 O ₄ . A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 described above was assembled in the same manner as in Example 1, except that the obtained LiMn _1.8 Ni _0.2 O ₄ powder was used as a positive electrode active material.

Example 15 A mixture of manganese nitrate powder, aluminum nitrate powder and lithium nitrate powder having a molar ratio of Li: Mn: Al of 1.02:
1.98: 0.02, and sufficiently dispersed using ethanol as a solvent. Then, while introducing an oxygen stream so that the oxygen concentration becomes 18% or more and 100% or less, 7
The product is sprayed into a reaction furnace maintained at a temperature of 00 ° C., and the obtained product is maintained so that the oxygen concentration becomes 95% or more. Then, a heat treatment is performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. Was. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn _1.98 Al _0.02 O ₄ . A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained LiMn _1.98 Al _0.02 O ₄ powder was used as a positive electrode active material.

Example 16 A mixture of manganese nitrate powder, lithium tetraborate powder and lithium nitrate powder having a molar ratio of Li: Mn: B of 1.02:
After sufficiently dispersing ethanol in a solvent such that the ratio becomes 1.98: 0.02, the oxygen concentration is from 18% to 100%.
Spraying into a reactor maintained at a temperature of 700 ° C. while introducing an oxygen gas stream as described below, and maintaining the resulting product so that the oxygen concentration becomes 95% or more,
Heat treatment was performed at 800 ° C. for 5 hours while pressurizing to 1 MPa. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn _1.98 B _0.02 O ₄ . A cylindrical nonaqueous electrolyte secondary battery as shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained LiMn _1.98 B _0.02 O ₄ powder was used as a positive electrode active material.

Example 17 A manganese nitrate powder, a lithium fluoride powder and a lithium nitrate powder were mixed at a molar ratio of Li: Mn: F of 1.02: 2: 0.
02, and sufficiently dispersed using ethanol as a solvent. Then, while introducing an oxygen stream so that the oxygen concentration becomes 18% or more and 100% or less, the reaction furnace was maintained at a temperature of 700 ° C. And the resulting product is maintained at an oxygen concentration of 95% or more, and then 1MP
As a result, a heat treatment was performed at 800 ° C. for 5 hours while the pressure was increased to as. When the obtained product was measured by X-ray diffraction,
Li _1.02 Mn ₂ F _0.02 O _3.98 was confirmed.
A cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained Li _1.02 Mn ₂ F _0.02 O _3.98 powder was used as a positive electrode active material.

Example 18 Manganese nitrate powder, aluminum nitrate powder, nickel nitrate powder, cobalt nitrate powder, and lithium tetraborate and lithium fluoride were mixed with Li: Mn: Ni: Co: B: Al:
The molar ratio of F is 1.02: 1.92: 0.02: 0.0
2: 0.02: 0.02, and sufficiently dispersed using ethanol as a solvent.
While introducing an oxygen gas stream so that the oxygen concentration is at least 100%, the solution is sprayed into a reaction furnace maintained at a temperature of 700 ° C., and is maintained at an oxygen concentration of 95% or more.
A heat treatment was performed at 800 ° C. for 5 hours while pressurizing to Pas. When the obtained product was measured by X-ray diffraction, it was found that Li _2.01 Mn _1.92 Co _0.02 Ni _0.02 Al _0.02 B _0.02
F _0.04 O _3.96 was confirmed. Li obtained
_2.01 Mn _1.8 Co _0.04 Ni _0.04 Al _0.04 B _0.04 F _0.04 O
_The cylindrical non-aqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that _3.96 powder was used as the positive electrode active material.

Comparative Example 3 A cathode active material having a D50 / r of 100 or more (r: 0.1, D50: 15.0) A manganese nitrate powder and a lithium nitrate powder having a molar ratio of Li: Mn of 1.02: 2. After sufficient dispersion using ethanol as a solvent so as to obtain, spray drying was performed. The obtained dried product was heated at a temperature of 650 ° C. for 5 hours while introducing an oxygen stream so that the oxygen concentration became 18% or more and 100% or less. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn ₂ O ₄ . The cylindrical nonaqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained iMn ₂ O ₄ powder was used as a positive electrode active material.

Comparative Example 4 A positive electrode active material having a D50 / r of less than 10 (r: 1.0, D50: 8.0) A manganese nitrate powder and a lithium nitrate powder having a molar ratio of Li: Mn of 1.02: 2. After sufficient dispersion using ethanol as a solvent, spray drying was performed. The obtained dried product was heated at a temperature of 700 ° C. for 48 hours while introducing an oxygen stream so that the oxygen concentration became 18% or more and 100% or less. When the obtained product was measured by X-ray diffraction, it was confirmed to be LiMn ₂ O ₄ . The cylindrical nonaqueous electrolyte secondary battery shown in FIG. 1 was assembled in the same manner as in Example 1 except that the obtained iMn ₂ O ₄ powder was used as a positive electrode active material.

The battery characteristics of Examples 1 to 18 and Comparative Examples 1 to 4 are as shown in Table 1. For each nonaqueous electrolyte secondary battery, charging was performed at a constant current of 400 mA up to 4.2 V, followed by a constant voltage of 4.2 V for a total of 8 hours, and then 400 mA, 2000 mA, and 4000 up to 2.7 V.
The discharge capacity when discharging at a constant current of mA was measured, and 40
The capacity retention ratio with respect to the capacity at the time of 0 mA discharge was determined. Also, after charging was performed at a constant current of 400 mA up to 4.2 V,
After a total of 8 hours at a constant voltage of 4.2 V,
The charge / discharge cycle characteristics when discharging at a constant current of 400 mA to 2.7 V were examined.

Table 1 D50 / r and characteristic value of the nonaqueous electrolyte secondary battery Capacity retention rate during discharge (%) Average discharge example number D50 / r 2000 mA 4000 mA Voltage (V) Cycle life ^* Example 1 25 92 80 3.67 510 Example 2 33 95 82 3.64 525 Example 3 48 96 83 3.65 530 Example 4 14 98 83 3.68 550 Example 5 25 90 71 3.62 510 Example 6 40 88 69 3.61 550 Example 7 50 88 70 3.64 535 Example 8 33 87 66 3.62 540 Example 9 50 85 67 3.63 510 Example 10 48 84 65 3.61 520 Example 11 29 83 62 3.62 550 Example 12 25 82 64 3.83 500 Example 13 40 84 72 3.82 540 Example 14 29 81 61 3.82 5 0 Example 15 33 85 70 3.81 530 Example 16 14 83 65 3.78 525 Example 17 48 81 63 3.75 540 Example 18 33 80 61 3.76 530 Comparative Example 1 100 67 35 3.56 530 Comparative Example 2 8 89 78 3.62 100 Comparative Example 3 150 62 34 3.68 500 Comparative Example 4 8 84 72 3.72 100 ^{* The} number of cycles in which the capacity reaches 80% of the initial capacity.

As shown in Table 1, the non-aqueous electrolyte secondary batteries of Examples 1 to 18 have a higher discharge potential and a higher current than the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 4. Excellent characteristics. Further, it can be seen that the cycle characteristics are significantly improved.

[0076]

As described above, according to the present invention,
A non-aqueous electrolyte secondary battery having a high discharge voltage, excellent large-current charge / discharge characteristics, and excellent cycle characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a cylindrical nonaqueous electrolyte secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Insulator 3 Electrode group 4 Positive electrode 5 Separator 6 Negative electrode 7 Insulating paper 8 Insulating sealing plate 9 Positive electrode terminal 10 Positive electrode lead

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 4/58 H01M 4/00-4/02 H01M 10/40

Claims (5)

(57) [Claims] (A) The general formula Li _x M _1-y A _y F _z O _2n-z
(Where 0.9 ≦ x ≦ 1.1, 0 ≦ y ≦ 0.5, 0 ≦
z ≦ 0.25, 1 ≦ n ≦ 2, M is at least one or more transition elements selected from Co, Ni, Mn, A is Co, N
(i) at least one element selected from i, Mn, B, and Al) as a positive electrode active material; (B) a negative electrode containing a compound that absorbs and releases lithium ions; and (C) a non-aqueous electrolyte secondary battery comprising an electrolyte solution in which an electrolyte is dissolved in a non-aqueous solvent, wherein the positive electrode active material is C
Form secondary particles consisting of primary particles having a crystal structure with axial orientation, and average length r of the primary particles in the short direction.
A non-aqueous electrolyte secondary battery, wherein a ratio D50 / r between the particle diameter D50 at which the volume cumulative frequency of the particle size distribution of the secondary particles reaches 50% is 10 ≦ D50 / r ≦ 50. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the ratio D50 / r satisfies 20 ≦ D50 / r ≦ 40. 3. r is 0.1 μm or more and 1 μm or less;
The non-aqueous electrolyte secondary battery according to claim 1. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein D50 is 0.2 μm or more and 50 μm or less. 5. The particle diameter of the composite oxide at which the volume cumulative frequency of the particle size distribution reaches 10, 50 and 90% is D, respectively.
The method according to claim 1, wherein when D, D50, and D90, 0.3 ≦ (D10 / D50) ≦ 0.8, and 1 ≦ (D90 / D50) ≦ 3. Non-aqueous electrolyte secondary battery.